The Sure grip is not that cheap but I bought one to try out. It was $25. You can use any aquarium style magnet. I have used normal magnets and sealed them in Silicone but the eventually the silicone failed. It might not have been thick enough or maybe the magentic field caused an issue. Not sure.
For those that don't want to fool with magnets, you can use acrylic to make hangers. Acrylic strips, a lighter and some nylon bolts/nuts will make a nice mount.
*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,